1. Field of the Invention
The present invention relates generally to an apparatus for manufacturing a bent or curved glass sheet, and more particularly to such a curved glass manufacturing apparatus which is equipped with improved bending and conveyor units. It also relates to a bending roll mechanism and a conveyor roll mechanism used in the bending unit and the conveyor unit, respectively.
2. Description of the Related Art
Various curved glass manufacturing apparatuses including a bending section and a conveyor system are known. Examples of such known apparatuses are disclosed in Japanese Patent Laid-open Publication No. SHO 54-85217 entitled xe2x80x9cMethod and Apparatus for Shaping Glass Sheets by Roll Formingxe2x80x9d, Japanese Patent No. 2690766 entitled xe2x80x9cConveyor Roll Structurexe2x80x9d, Japanese Patent Laid-open Publication No. HEI 3-150232 entitled xe2x80x9cMethod and Apparatus for Bending Glass Sheetsxe2x80x9d, Japanese Patent Laid-open Publication No. HEI 3-174334 entitled xe2x80x9cMachine and Process for Manufacturing Curved Glass Sheetsxe2x80x9d, and Japanese Patent Laid-open Publication No. HEI 4-275929 entitled xe2x80x9cMethod and Apparatus for Bending Glass Sheetsxe2x80x9d.
The apparatus shown in Japanese Patent Laid-open Publication No. SHO 54-85217 includes a bending section having a series of horizontally arranged upper forming rolls of convex cross-sectional shape and a series of horizontally arranged lower forming rolls of concave cross-sectional shape disposed in vertical juxtaposition so that a flat glass sheet, as it is passed between the upper and lower forming rolls, is bent into a desired curvature.
The upper and lower forming rolls are segmented so as to reduce the difference in circumferential speed between a large-diameter portion and a small-diameter portion of each forming roll.
However, since the difference in circumferential speed cannot be fully taken up or canceled by the segmented structure of the forming rolls, a mark or scar may be produced on opposite surfaces of the glass sheet due to slip occurring between the surfaces of the glass sheet and circumferential surfaces of the upper and lower forming rolls.
Additionally, since these parts of the forming rolls which correspond in position to parting lines between the adjacent segmented pieces do not contact with the surfaces of glass sheet during bending operation, the glass sheet while being bent by such forming rolls is likely to be strained or distorted.
Furthermore, due to the segmented structure, the forming rolls of the known apparatus is not easily adaptable to the manufacture of a curved glass sheet with different curvature.
Japanese Patent No. 2690766 discloses a conveyor roll which, as shown here in FIG. 25, includes a core member 101 bent into a desired curvature, and a helical coil spring member 102 rotatably wound around the core member 101. By rotating the spring member 102, glass sheets 103 which have been bent into a desired curvature are conveyed to a subsequent processing section.
To secure smooth rotation of the spring member 102 around the core member 101, a certain clearance S must be provided between the core member 101 and the spring member 102. However, especially when the core member 101 is used with a relatively small curvature, the clearance S may allow the spring member 102 to become eccentric to the core member 101, thus producing up-and-down movement or pitching of the glass sheets 103 during conveyance along a succession of such conveyor rolls 100. Due to the pitching, very small undulations are formed on opposite surfaces of the conveyed curved glass sheet, which may produce distortion or warping of image when an image is formed on such undulated surface of the curved glass sheet 103 by light either reflected from the undulated glass sheet surface or transmitted through the glass sheet 103.
Additionally, to cope with the conveyance of glass sheets of different curvatures, replacement of the core member 101 with another core member is unavoidable. This requirement may result in a considerably reduced productivity of the curved glass manufacturing apparatus.
The present invention is conceived to solve the foregoing problems associated with the prior art.
A more specific object of the present invention is to provide a curved glass manufacturing apparatus which is capable of manufacturing a curved glass sheet with high qualities and is readily adaptable to the manufacture of various curved glass sheets of different curvatures.
A further object of the present invention is to provide a curved glass manufacturing apparatus having a bending unit which is capable of bending a flat glass sheet into a desired curvature without producing a slip between forming rolls and the glass sheet and is readily adaptable to the manufacture of various curved glass sheets of different curvatures.
Another object of the present invention is to provide a curved glass manufacturing apparatus having a conveyor unit which is capable of achieving a reliable conveyance of curved glass sheets by virtue of little eccentricity of the conveyance roll and is readily adaptable to the conveyance of various curved glass sheets of different curvatures.
According to a first aspect of the present invention, there is provided a curved glass manufacturing apparatus comprising at least one roll-forming unit composed of at least one upper forming roll mechanism and at least one lower forming roll mechanism cooperating with the upper forming roll mechanism to form a heated flat glass sheet into a curved glass sheet of a desired curvature. Each of the upper and lower forming roll mechanisms includes a forming roll having a resilient rod covered with a cover member except opposite end portions thereof, a pair of support members rotatably supporting the opposite end portions of the resilient rod while allowing the resilient rod to tilt about the support members, a bending unit coupled with at least one of the opposite end portions of the resilient rod for applying to the at least one end portion an external force tending to flex the forming roll into either an upwardly arched configuration or a downwardly arched configuration, and at least one backup roller unit being in rolling engagement with the forming roll to maintain the arched configuration of the forming roll.
Each of the upper and lower forming roll mechanisms may further include a drive source coupled with the other end portion of the resilient rod to rotate the forming roll.
Preferably, the resilient rod is composed of an elongated core member of resilient material, a plurality of resilient strands laid longitudinally on a peripheral surface of the core member in close juxtaposition around the core member, and a helical coil spring wound around the resilient strands to tightly bind together the resilient strands and the core member.
The cover member may be a seamless tube having a knit structure formed of a glass fiber, ceramic fiber, metal fiber, aramid fiber or the combination thereof. Alternatively, the cover member may be a continuous tape wound around the resilient rod and having a woven structure formed of the same material as the seamless knit tube.
Preferably, the support members each include a fixed housing having a spherical hole, and a spherical segment member pivotally received in the spherical hole and rotatably supporting one of the opposite end portions of the resilient rod.
In one preferred form, the bending unit includes a tubular holder pivotally supported by one of the support members and having an axial blind hole in which the one end portion of the resilient rod is slidably and rotatably received, and an adjustment screw threaded through a closed end of the tubular holder into the axial blind hole and adapted to be turned to displace the one end portion of the resilient rod in an axial inward direction for causing the forming roll to flex in the arched configuration. The bending unit may further include a compression coil spring and a steel ball in the axial blind hole of the tubular holder and disposed between the adjustment screw and the one end portion of the resilient rod, a first spring seat disposed between the adjustment screw and one end of the compression coil spring, and a second spring seat disposed between the other end of the compression coil spring and the steel ball. The compression coil spring preferably has a resiliency greater than that of the resilient rod of the forming roll. The tubular holder is firmly fitted in the central hole of the spherical segment member of the support member.
In another preferred form, the bending unit includes a socket having a spherical hole, a spherical segment member pivotally received in the spherical hole of the socket and having a central hole in which the one end portion of the resilient rod is rotatably received, a fixed support nut having a vertically extending threaded hole, and a screw shaft threaded through the fixed support nut and having an end connected to the socket, the screw shaft being adapted to be turned to move the socket and the spherical segment member in a vertical direction for causing the resilient rod to tilt about the support members.
Preferably, the backup roller unit includes a roller holder, a pair of support rollers rotatably mounted on the roller holder in symmetric relation to one another about a vertical plane passing through an axis of the forming roll for rolling engagement with a circumferential surface of the forming roll, a fixed support nut having a vertically extending threaded hole, and a screw shaft threaded through the support nut and connected at an end to the roller holder, the screw shaft being adapted to be turned to move the support roller in vertical directions toward and away from the forming roll.
For use in the manufacture of a bidirectionally curved glass sheet having curvatures about two mutually perpendicular axes thereof, the roll-forming unit preferably includes one upper forming roll mechanism and two lower forming roll mechanisms. The respective forming rolls of the upper and lower forming roll mechanisms are arranged to match a curvature to be imparted to the heated glass sheet about an axis thereof extending orthogonally to the axes of the forming rolls. The upper forming roll mechanism may be vertically movable, and the lower forming roll mechanisms may be horizontally movable toward and away from a vertical plane along which the upper forming roll mechanism is movable. The roll-forming unit may further include two second lower forming roll mechanisms disposed between the two lower forming roll mechanisms in symmetric relation with each other about a vertical plane passing through the axis of the forming roll of the upper forming roll mechanism. The upper forming roll mechanism is movable along the vertical plane, the two lower forming roll mechanisms are fixed in position, and the two second lower forming roll mechanisms are horizontally movable toward and away from the vertical plane.
The curved glass manufacturing apparatus may further include a series of horizontally arranged conveyor roll mechanisms disposed downstream of the roll-forming unit for conveying the curved glass sheet a downstream direction. Each of the conveyor roll mechanisms comprises a conveyor roll including a resilient rod and a plurality of work supporting circular disks attached to the resilient rod at intervals along the length of the resilient rod, a pair of support members rotatably supporting opposite end portions of the resilient rod while allowing the resilient rod to tilt about the support members, and at least one bending support members acting on the resilient rod to pull or push the resilient rod in a direction orthogonal to the axis of the resilient rod to flex the resilient rod into a curvature complemental to the desired curvature of the curved glass sheet.
Preferably, the resilient rod of the conveyor roll is composed of an elongated core member of resilient material, a plurality of resilient strands laid longitudinally on a peripheral surface of the core member in close juxtaposition around the core member, and a helical coil spring wound around the resilient strands to tightly bind together the resilient strands and the core member.
Like in the forming roll mechanism, the support members of the conveyor roll mechanism each include a fixed housing having a spherical hole, and a spherical segment member pivotally received in the spherical hole and rotatably supporting one of the opposite end portions of the resilient rod.
In one preferred form, the bending support member includes a horizontal cross member extending between the support members in lateral spaced relation to the conveyor roll, a socket having a spherical hole, a spherical segment member pivotally received in the spherical hole in the socket and having a central hole in which a longitudinal portion of the resilient rod is rotatably received, a screw shaft extending vertically through the cross member and connected at one end to the socket, and first and second nuts threaded with the screw shaft on opposite sides of the cross member. The second nut is located remotely from the socket as compared to the first nut and is preferably comprised of a lock nut with handle having a wheel-like handle portion and a nut portion integral with a central portion of the handle portion. The cross member may have an oblong hole extending in a direction parallel to the axis of the resilient rod, and the screw shaft extends through the oblong hole for enabling positional adjustment of the bending support member in the longitudinal direction of the resilient rod.
In another preferred form, the bending support member includes a horizontal cross member extending between the support members in lateral spaced relation to the conveyor roll, a socket having a spherical hole, a spherical segment member pivotally received in the spherical hole in the socket and having a central hole in which a longitudinal portion of the resilient rod is rotatably received, and a turnbuckle interconnecting the socket and the cross member. The turnbuckle includes a first screw rod having a left-hand thread and connected at one end to the socket, a second screw rod having a right-hand thread, a stay pivotally connected to the cross member and firmly connected to one end of the second screw, and a sleeve having opposite ends threaded with the left-hand and right-hand threads of the first and second screw rods with the respective other ends of the first and second screw rods facing each other. Preferably, the stay is pivotally connected to the cross member by a pivot pin extending through an oblong hole formed in the cross member for enabling adjustment of the position of the bending support member in the longitudinal direction of the resilient rod.
The conveyor roll mechanism may further include a drive source coupled with one end of the resilient rod to rotate the conveyor roll.
The conveyor roll mechanisms may be arranged in pairs each composed of an upper conveyor roll mechanism and a lower conveyor roll mechanism cooperating with each other to convey the curved glass sheet while gripping the curved glass sheet between respective conveyor rolls of the upper and lower conveyor roll mechanisms.
According to a second aspect of the present invention, there is provided a forming roll mechanism for roll-forming a heated flat glass sheet into a curved glass sheet of a desired curvature. The forming roll mechanism comprises a forming roll having a resilient rod covered with a cover member except opposite end portions thereof, a pair of support members rotatably supporting the opposite end portions of the resilient rod while allowing the resilient rod to tilt about the support members, a bending unit coupled with at least one of the opposite end portions of the resilient rod for applying to the at least one end portion an external force tending to flex the forming roll into either an upwardly arched configuration or a downwardly arched configuration, and at least one backup roller unit being in rolling engagement with the forming roll to maintain the arched configuration of the forming roll.
According to a third aspect of the present invention, there is provided a conveyor roll mechanism for use in the manufacture of a curved glass sheet for conveyance of the curved glass sheet. The conveyor roll mechanism comprises a conveyor roll including a resilient rod and a plurality of work supporting circular disks attached to the resilient rod at intervals along the length of the resilient rod, a pair of support members rotatably supporting opposite end portions of the resilient rod while allowing the resilient rod to tilt about the support members, and at least one bending support members acting on the resilient rod to pull or push the resilient rod in a direction orthogonal to the axis of the resilient rod to flex the resilient rod into a curvature complemental to the desired curvature of the curved glass sheet.
The above and other objects, features and advantages of the present invention will become manifest to those versed in the art upon making reference to the following description and accompanying sheets of drawings in which preferred structural embodiments incorporating the principle of the invention are shown by way of illustrative examples.